KR20140081101A - Liquid crystal display device and driving method thereof - Google Patents

Abstract

The present invention relates to a liquid crystal display device. Particularly, the technical object is to provide the liquid crystal display device and a driving method thereof, capable of changing inversion methods according to a preset period. For this, the liquid crystal display device according to the present invention includes a liquid crystal panel which includes pixels in each region defined by the intersection of gate lines and data lines; and a driving unit which changes at least two inversion methods for driving the liquid crystal panel according to the preset period.

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal display (LCD)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display using various inversion methods and a driving method thereof.

2. Description of the Related Art As various portable electronic devices such as a mobile communication terminal, a smart phone, a tablet computer, a notebook computer and the like are developed, a demand for a flat panel display device that can be applied to the portable electronic device is gradually increasing. As such a flat panel display device, a liquid crystal display device, a plasma display panel (PDP), a field emission display device, an organic light emitting display device Research.

Among the flat panel display devices, liquid crystal display devices are most widely commercialized at present because of advantages of mass production technology, ease of driving means, and realization of high image quality.

The liquid crystal display device drives the liquid crystal panel by various inversion methods in order to prevent the deterioration of the liquid crystal and to improve the display quality. Inversion methods include a frame inversion system, a line inversion system, a column inversion system, a dot inversion system, or a Z-inversion system Z-Inversion System) method.

FIG. 1 is an exemplary diagram for explaining a general line inversion method, in particular, a horizontal one line inversion method. FIG. 2 is an exemplary diagram for explaining a general dot-inversion method. In particular, FIG. 2 shows a vertical 1 dot, horizontal 1 dot, and Vertical 1 dot (Horizon 1Dot Inversion) method.

Among the inversion methods described above, the line inversion method inverts the polarity of the data voltage supplied to the pixels in units of horizontal lines and inverts the data voltages in units of frames, as shown in FIG.

1 (b) shows the polarity of the data voltage in the (2n + 1) th frame, and FIG. 1 (b) shows the polarity of the data voltage in the In the version method, the polarity of the data voltage supplied to the pixels is inverted in units of horizontal lines in one frame, and inverted in units of frames in the case of the same horizontal line.

Among the inversion methods described above, the dot inversion method inverts the polarity of the data signal supplied to the pixels in dot units and inverts the data signals in units of frames, as shown in FIG.

2 (b) shows the polarity of the data voltage in the (2n + 1) -th frame, and FIG. 2 (b) shows the polarity of the data voltage in the In the version with a horizontal one dot, the polarity supplied to the pixels is inverted in units of adjacent pixels in one frame, and inverted in units of frames when they are the same pixel.

In addition, the above-described inversion methods inverts the polarity of the data voltage supplied to each of the pixels into various shapes.

The conventional inversion methods as described above reverse the polarity of dots for each frame and do not change the inversion method.

That is, in the conventional inversion methods, the polarity of one horizontal line is inverted for every frame (one horizontal line inversion method), or the polarity of vertical one dot and horizontal one dot is reversed every frame (vertical one dot , Version with one horizontal dot), or the polarity of the entire dot is reversed every frame (frame inversion method).

In the liquid crystal display device using the conventional inversion method as described above, since the polarity of dots changes every frame and the inversion method is not changed as described above, the following problems occur.

First, even within the same dot, there is a difference in transmittance depending on the polarity.

Second, the difference in transmittance according to the polarity difference is compared with the adjacent dot, and a flicker occurs in a glance.

Third, the flicker phenomenon becomes worse in a screen which is vulnerable to a specific inversion driving method.

That is, in a liquid crystal display device using a conventional inversion method, a capacitance deviation in the panel occurs due to a difference in a process deviation of the liquid crystal panel and a driving voltage of the liquid crystal. In this case, if the polarity of the positive / negative polarity is different at one dot (Dot), a difference in transmittance occurs and a flicker occurs visually. Moreover, there is a limitation in improving the flicker level due to the panel deviation in one inversion method, because there is a screen which is vulnerable to flicker, regardless of the inversion method (inversion driving method).

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a liquid crystal display device and a driving method thereof that can change the inversion modes for every predetermined period.

According to an aspect of the present invention, there is provided a liquid crystal display device comprising: a liquid crystal panel having pixels formed in regions defined by intersections of gate lines and data lines; And a driving unit for changing at least two or more inversion methods for driving the liquid crystal panel every predetermined period.

According to an aspect of the present invention, there is provided a method of driving a liquid crystal display device, including: changing at least two inversion methods by a predetermined period; And changing the image data to data voltages according to the inversion method, and outputting the data voltages to the gate line.

According to the present invention, the flicker can be reduced because the inversion methods are changed every predetermined period.

That is, when the periodic inversion method is changed, the transmittance change due to the polarity difference with respect to the neighboring dots periodically changes, and the level of flicker may be reduced.

In particular, when the four inversion schemes are periodically changed, the flicker level can be reduced to a maximum of about a quarter of the level, as compared with the case where one inversion scheme is used in calculation.

1 is an exemplary diagram for explaining a general line inversion method;
2 is an exemplary diagram for explaining a general dot inversion method;
3 is a view schematically showing a liquid crystal display device according to the present invention.
4 is an exemplary view showing the configuration of the driving unit shown in Fig.
5 is an exemplary view showing a configuration of the data driver shown in FIG.
6 is an exemplary view showing a configuration of the control unit shown in Fig.
7 is a diagram illustrating polarities of data voltages output to a liquid crystal panel of a liquid crystal display device according to the present invention.
8 is a graph comparing flicker levels in a liquid crystal display device according to the present invention and flicker levels in a conventional liquid crystal display device.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a view schematically showing a liquid crystal display device according to the present invention, FIG. 4 is an exemplary view showing the configuration of the driving part shown in FIG. 3, and FIG. 5 is an exemplary view showing the configuration of the data driving part shown in FIG. And FIG. 6 is an exemplary view showing the configuration of the control unit shown in FIG.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a driving method thereof, which can reduce flicker by changing inversion modes every predetermined period.

According to the present invention, since the inversion method is sequentially changed in a specific frame unit, the flicker level generated by comparing the transmittance difference due to the polarity change between the adjacent dots is compared with the neighboring dots.

That is, according to the present invention, even if a weak image is generated in the flicker in a certain inversion method, since the inversion method is changed every predetermined frame, the flicker due to the difference in transmittance depending on the polarity can be reduced.

3, the liquid crystal display 100 according to the present invention includes pixels formed in regions defined by intersections of gate lines GL and data lines DL, And a driving unit 500 for changing at least two or more inversion methods for driving the liquid crystal panel 100 every predetermined period.

First, the liquid crystal panel 100 includes a lower substrate and an upper substrate bonded together with a liquid crystal layer (not shown) interposed therebetween.

A plurality of data lines DL, a plurality of gate lines GL intersecting with the data lines DL, and a plurality of data lines DL are formed on a lower substrate (TFT substrate) of the liquid crystal panel 100, A plurality of TFTs (Thin Film Transistors) formed at intersections of lines, a plurality of pixel electrodes for charging a data voltage to pixels formed for each intersection region of the data lines and the gate lines, A common electrode for driving the liquid crystal filled in the liquid crystal layer is formed.

Subpixels are formed in the regions where the data lines DL and the gate lines GL intersect. The subpixels may be composed of a red subpixel, a green subpixel, or a blue subpixel, and adjacent red subpixels, green subpixels, and blue subpixels may constitute one unit pixel (UP) do.

Each of the plurality of subpixels includes a thin film transistor T connected to one adjacent gate line and one data line adjacent thereto, a pixel electrode (not shown) connected to the thin film transistor T and a plurality of pixel electrodes And a common electrode (not shown) to which a common voltage is supplied.

A black matrix BM and a color filter are formed on an upper substrate (CF substrate) of the liquid crystal panel 100. The common electrode may be formed on the upper substrate (CF substrate).

Polarizing plates POL1 and POL2 are attached to the upper substrate and the lower substrate of the liquid crystal panel 100, respectively, and an alignment layer for setting the pretilt angle of the liquid crystal is formed on the inner surface in contact with the liquid crystal.

A column spacer CS for maintaining a cell gap may be formed between the upper substrate and the lower substrate of the liquid crystal panel 100.

The liquid crystal panel 100 is provided with a display area A in which an image is output and non-display areas 111, 112 and 113 formed outside the display area and not outputting an image.

In the display area A of the liquid crystal panel 100, the gate lines GL and the data lines DL are formed to intersect with each other.

The driving unit 500 is formed in a first non-display area 111 of the non-display area of the liquid crystal panel 100. The data line DL is connected to a data connection line (Not shown).

The second non-display region 112 and the third non-display region 113 of the non-display region of the liquid crystal panel 100 are connected to the gate connection line (115) are formed.

Second, the driver 500 sequentially outputs a scan signal to the gate connection lines and outputs a data voltage to the data lines. As shown in FIG. 4, A data driver 300 for outputting a data voltage to a data line DL formed in the panel 100, and a data driver 300 for outputting a data voltage to the gate line GL. And a control unit 400 for controlling the functions of the driving unit and the data driving unit.

First, the data driver 300 converts the digital image data transmitted from the controller 400 into a data voltage, and supplies the data voltage of one horizontal line for each horizontal period, which is supplied with a scan signal to the gate line, Data lines.

That is, the data driver 300 converts the image data into the data voltage using gamma voltages supplied from a gamma voltage generator (not shown), and outputs the data voltage to the data line. 5, the data driver 300 includes a shift register unit 310, a latch unit 320, a digital-analog converter (DAC) 330, and an output buffer 340 .

The shift register unit 310 generates a sampling signal using data control signals (SSC, SSP, etc.) received from the controller 400.

The latch unit 320 latches the digital image data Data sequentially received from the controller 400 and simultaneously outputs the latched digital image data to the digital-analog converter (DAC) 330.

The digital-to-analog converter 330 converts the image data transmitted from the latch unit 320 into a positive or negative data voltage and outputs the same. That is, the digital-analog converter 330 converts the image data into a positive or negative data voltage (data signal) using the polarity control signal POL transmitted from the controller, and outputs the data voltage to the data lines do.

At this time, the polarity control signal POL is changed into various forms from the controller 400 and input to the digital-analog converter 300.

The digital-analog converter 330 converts the image data into the data voltage using a high-level driving voltage VDD.

The output buffer 340 outputs the positive or negative data voltage transmitted from the digital-analog converter 330 to the data line (not shown) of the panel according to the source output enable signal SOE transmitted from the control unit DL).

Next, the controller 400 controls the gate drive ICs (not shown) using timing signals input from an external system, that is, a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, and a data enable signal DE. The data driver 300 generates a gate control signal GCS for controlling the operation timing of the data driver 300 and a data control signal DCS for controlling the operation timing of the data driver 300, .

That is, the control unit 400 arranges the input image data input from the external system according to the structure and characteristics of the panel 100, and outputs the aligned image data to the data driver 300 send.

For this purpose, the controller 400 may include a data arrangement unit 430, as shown in FIG.

The control unit 400 may control the driving of the data driver 400 using the timing signals transmitted from the external system, that is, the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the data enable signal DE. The data driver 300 and the gate driver 200 generate a data control signal DCS for controlling the data driver 300 and a gate control signal GCS for controlling the gate driver 200, As shown in FIG.

To this end, the control unit 400 may include a control signal generator 420, as shown in FIG.

The gate control signals GCS generated by the control signal generator 420 include a gate start pulse GSP, a gate shift clock GSC, a gate output enable signal GOE, a gate start signal VST, (GCLK).

The data control signals generated by the control signal generator 420 include a source start pulse SSP, a source shift clock signal SSC, a source output enable signal SOE and a polarity control signal POL .

In particular, the control signal generator 420 according to the present invention generates the polarity control signal POL using various inversion methods every predetermined period, and transmits the polarity control signal POL to the data driver 300 .

Here, the predetermined period may be set in units of frames, such as one frame, two frames, three frames, or four frames.

The various inversion methods are a version method (V1H1) with vertical 1 dot / horizontal 1 dot, a version method (V2H1) with vertical 2 dot / horizontal 1 dot, a version method with V1H2 ), And a version system (V2H2) in which vertical 2 dots / horizontal 2 dots are used. In addition to the above inversion systems, a frame inversion system, a line inversion system, a column inversion system And the like may be further included.

That is, the controller 400 selects at least two of various inversion schemes currently used in the liquid crystal display device, and selects the polarity control signal POL according to the inversion mode and the predetermined period, And transmits the generated data to the data driver 300.

Meanwhile, the control unit 400 may include a storage unit 450 for storing the inversion method and the predetermined period. However, the storage unit 450 may be formed in the driving unit 500 instead of the control unit 400. [

Lastly, the gate driver 200 includes stages for sequentially outputting a scan signal to the gate lines GL.

The gate driver 200 may be formed inside the driver 500 formed of an integrated circuit (IC). In this case, the stages are also formed inside the driving unit 500.

The stages may be formed in the second non-display area 112 and the third non-display area 113 in the form of a gate in parallel (GIP).

7 is a diagram illustrating polarities of data voltages output to a liquid crystal panel of a liquid crystal display device according to the present invention. FIG. 8 is a graph comparing flicker levels in a conventional liquid crystal display device with a flicker level in a liquid crystal display device according to the present invention, wherein (a) is a graph showing flicker levels in a conventional liquid crystal display device, and ) Is a graph showing the flicker level according to the present invention.

First, the inversion method applied to the present invention may be all the inversion methods currently used as described above. That is, in the liquid crystal display device and the driving method thereof according to the present invention, a version system (V1H1) with vertical 1 dot / horizontal 1 dot, a version system (V2H1) with vertical 2 dot / horizontal 1 dot, vertical 1 dot / horizontal 2 dot The inversion method V1H2, the vertical 2-dot / horizontal 2-dot version method V2H2, the frame inversion method, the line inversion method, the column inversion method and the z inversion method can be applied. , Two or more are applied.

Hereinafter, for convenience of description, a version system (V1H1) with vertical 1 dot / horizontal 1 dot, a version system (V2H1) with vertical 2 dot / horizontal 1 dot, a version system (V1H2) with vertical 1 dot / horizontal 2 dot, The present invention is described by applying the version system (V2H2) with 2 dots / horizontal 2 dots to the present invention.

Next, the present invention may sequentially change the inversion methods at least every one frame.

As described above, when the present invention uses four inversion schemes, the controller 400 may change the inversion schemes every frame.

That is, the driving unit 500 outputs the data voltage to the data line in accordance with the version scheme (V1H1) in which the first frame is vertical 1 dot / horizontal 1 dot, and the second frame is vertical 2 dot / horizontal 1 dot Outputs a data voltage to the data line according to a version scheme (V1H2) having a vertical 1 dot / horizontal 2 dot in a third frame, and outputs a data voltage to the data line according to a version scheme (V1H2) The data voltage may be output to the data line in accordance with a version method (V2H2) of vertical 2 dot / horizontal 2 dot.

In addition, the driving unit 500 may sequentially output the four inversion schemes for every four frames.

That is, as shown in FIG. 7, the driving unit 500 drives the data voltage according to a version scheme (V1H1) having vertical 1 dot / horizontal 1 dot during the (n) th to (n + (N + 5) th to (n + 8) th frames, the data voltage is output to the data line in accordance with a version method (V2H1) of vertical 2 dot / horizontal 1 dot for the (N + 13) th frame to the (n + 16) th frame during the (n + 1) th to (n + (N + 17) th frame to the (n + 20) th frame, the data voltage is output to the data line in accordance with a version method (V2H2) of 2 vertical dots / The data voltage can be output to the data line according to the inversion method (V1H1).

Here, the output order of the four inversion schemes may be variously changed.

That is, the driving unit 500 includes a version system (V1H1) with vertical 1 dot / horizontal 1 dot, a version system (V1H2) with vertical 1 dot / horizontal 2 dot, a version system with vertical 2 dot / horizontal 1 dot V2H1) and the vertical two-dot / horizontal two-dot version method (V2H2).

In addition, the driving unit 500 may change various inversion schemes as described above to various periods and orders and output them.

On the other hand, according to the present invention as described above, the level of flicker is improved as shown in FIG. FIG. 8A is a graph showing the flicker level in a conventional liquid crystal display device, particularly, a graph showing the flicker procedure in a liquid crystal display device driven by a version method with vertical 2 dot / horizontal 1 dot. FIG. 8B is a graph showing the flicker level according to the present invention. In particular, a version system (V1H1) with vertical 1 dot / horizontal 1 dot, a version system (V2H1) with vertical 2 dot / horizontal 1 dot, Is a graph showing a flicker procedure in a liquid crystal display apparatus driven in the order of a dot / horizontal 2 dot inversion system ((V1H2) and a vertical 2 dot / horizontal 2 dot version system (V2H2).

That is, it can be seen from FIG. 8 that the level of flicker in the liquid crystal display according to the present invention is improved as compared with the conventional liquid crystal display.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: liquid crystal display panel 200: gate driving circuit
300: driving integrated circuit 400:
500:

Claims (10)

A liquid crystal panel in which pixels are formed for each region defined by the intersection of gate lines and data lines; And
And a driving unit for changing at least two or more inversion methods for driving the liquid crystal panel every predetermined period. The method according to claim 1,
The driving unit includes:
Wherein the at least two inversion methods are sequentially changed at least every one frame. The method according to claim 1,
The driving unit includes:
And four inversion methods are sequentially changed for each frame. The method according to claim 1,
The driving unit includes:
Wherein four inversion methods are sequentially changed for every four frames. 5. The method of claim 4,
The four inversion methods include a version method (V1H1) with vertical 1 dot / horizontal 1 dot, a version method (V2H1) with vertical 2 dot / horizontal 1 dot, a version method with vertical 1 dot / horizontal 2 dot V1H2) and a version system (V2H2) in which vertical 2 dots / horizontal 2 dots are used. Changing at least two or more inversion methods by a predetermined period; And
And changing the image data to data voltages according to the inversion method, and outputting the data voltages to a gate line. The method according to claim 6,
Wherein changing the inversion schemes comprises:
Wherein the at least two inversion methods are sequentially changed at least every one frame. The method according to claim 6,
Wherein changing the inversion schemes comprises:
And four inversion methods are sequentially changed for each frame. The method according to claim 6,
Wherein changing the inversion schemes comprises:
Wherein the four inversion methods are sequentially changed for every four frames. 10. The method of claim 9,
The four inversion methods include a version method (V1H1) with vertical 1 dot / horizontal 1 dot, a version method (V2H1) with vertical 2 dot / horizontal 1 dot, a version method with vertical 1 dot / horizontal 2 dot V1H2), and a vertical 2 dot / horizontal 2 dot version system (V2H2).

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